Magnetic field effects on the surfactant concentration over ferrofluid droplet surfaces in shear flows

We investigate the impact of a magnetic field on surfactant concentration and interfacial forces across droplet surfaces within shear flows. Our analysis centers on a single two-dimensional ferrofluid droplet covered with surfactants, suspended in an immiscible, non-magnetizable liquid. The model combines incompressible Navier-Stokes equations and Maxwell's equations in the superparamagnetic limit in the single-fluid formulation, augmented by terms accounting for Marangoni, capillary, and magnetic forces at the droplet interface. We solve the surfactant convection-diffusion equation at the surface, while a non-linear Langmuir equation of state relates surfactant concentration to surface tension. The model is numerically solved using finite differences, a level-set method for multiphase flow computation, and the closest-point method for concentration equation. Our findings reveal that even though the surfactant is magnetically neutral, the presence of a magnetic field significantly modifies its distribution at the interface. A magnetic field perpendicular to the primary flow direction shifts the maximum concentration zone from the droplet tips toward the flow vorticity direction, while a parallel field produces the opposite effect. Alterations in surfactant distribution directly impact the surface tension field, offering a potential wireless means of controlling droplet dynamics.

P4132Decreased myocardial native T1 times and impaired myocardial contractility in young anabolic androgenic steroids users

Background

Anabolic androgenic steroids (AAS) have been associated with several injuries on the cardiovascular system. AAS abuse may have a direct toxic effect on the myocardium that could lead to cardiac function and structure alterations. Clinical and forensic cases have been reported myocardial fibrosis in AAS users. Myocardial fibrosis increases the risk of heart failure and sudden death. However, recent studies did not show evidence of focal myocardial fibrosis and diffuse myocardial fibrosis in AAS users using T1-mapping techniques. Thus, it remains unclear the association between AAS and cardiac structure alterations.

Purpose

The aim of this study was to evaluate cardiac structure by cardiovascular magnetic resonance (CMR) imaging with late-gadolinium enhancement (LGE), cardiac T1-mapping and extracellular volume measurements (ECV). Additionally, we also evaluated the cardiac contractility by CMR and echocardiography in young AAS users.

Methods

Twenty strength-trained AAS users (AASU) age 29±5 yr, 20 age-matched strength-trained AAS nonusers (AASNU), and 10 sedentary controls (SC) were enrolled. Cardiac structure was assessed by LGE, native T1-mapping and ECV. Cardiac contractility was evaluated as cardiac strain measured by CMR (feature tracking imaging technique) and echocardiography (speckle tracking technique).

Results

Global native T1 times [753 (683–870) vs 916 (815–1239) vs 1205 (825–1242) ms, respectively, p=0.03], and native T1 times at the left ventricle mid-ventricular slice [813 (695–1096) vs 922 (825–1095) vs 1140 (840–1322) ms, respectively, p=0.03] were lower in AASU compared with AASNU and SC. Mid-ventricular ECV was similar between AASU, AASNU and SC (22±6 vs 23±4 vs 24±4%, respectively, p=0.37). Focal myocardial fibrosis was found in 2 individuals (11%) of AASU. The mid anteroseptal and mid inferoseptal were the most affected segments. The total estimated mass of the LV mass was 1.25 g (0.65%). Three participants of SC showed focal myocardial fibrosis. The mid anterolateral, mid inferolateral and mid inferomedial were the most affected segments. The total estimated mass of the LV mass was 3.43 g (2.30%). In contrast, none of the AASNU had myocardial fibrosis. By CMR, AASU showed a lower medial radial strain (30±8 vs. 38±6%, p<0.01), medial circumferential strain (−17±3 vs −20±2%, p<0.01) and global longitudinal strain (−17±3 vs −20±3%, p<0.01) compared with AASNU. Echocardiography also demonstrated a lower 4CH longitudinal strain in AASU compared with AASNU (−15.5±3 vs −18.3±2%, p=0.03). Moreover, the AASU shower a higher left ventricle mass compared with AASNU and SC (185±20 vs 130±17 vs 112±14 g, respectively, p<0.01).

Conclusion

This study indicates that AAS abuse may be associated with decreased myocardial native T1 times, impaired myocardial contractility and focal myocardial fibrosis. These myocardial structural and functional alterations may be associated to unadapted cardiac hypertrophy in young AAS users.

Acknowledgement/Funding

Fundação de Amparo à Pesquisa do Estado de São Paulo [FAPESP], Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (Capes).

Chronic Cadmium Exposure Accelerates the Development of Atherosclerosis and Induces Vascular Dysfunction in the Aorta of ApoE-/- Mice

Cadmium exposure is related to cardiovascular diseases, including hypertension, atherosclerosis, increased oxidative stress, endothelial dysfunction, and specific biochemical changes induced by this metal. Thus, we aimed to investigate whether cadmium exposure induces endothelial dysfunction, accelerates atherosclerotic plaque formation in the aorta, and enhances oxidative stress in apolipoprotein E knockout (ApoE^-/-) mice. Experiments were performed in 14-week-old male wild-type and ApoE^-/- mice. ApoE^-/- mice received cadmium (CdCl₂ 100 mg/L in drinking water for 28 days) or vehicle (distilled water). After treatment, vascular reactivity to phenylephrine, acetylcholine, and sodium nitroprusside was analyzed using isolated aorta. Bone marrow cells were isolated to assess the production of nitric oxide and reactive oxygen and nitrogen species. ApoE^-/- cadmium-treated mice had higher cholesterol levels than non-exposed mice. Cadmium exposure decreased the vasodilatation response to acetylcholine in aortic ring of ApoE^-/- mice, though no changes in phenylephrine or sodium nitroprusside responses were observed. L-NAME reduced vasodilator responses to acetylcholine; this effect was lower in ApoE^-/- cadmium-treated mice, suggesting reduction in nitric oxide (NO) bioavailability. Moreover, in bone marrow cells, cadmium decreased cytoplasmic levels of NO and increased superoxide anions, hydrogen peroxide, and peroxynitrite in ApoE^-/- mice. Morphological analysis showed that cadmium exposure increased plaque deposition in the aorta by approximately 3-fold. Our results suggest that cadmium exposure induces endothelial dysfunction in ApoE^-/- mice. Moreover, cadmium increased total cholesterol levels, which may promote the early development of atherosclerosis in the aorta of ApoE^-/- mice. Our findings support the hypothesis that cadmium exposure might increase the risk of atherosclerosis.

Alterations in morphometric and organosomatic indices and histopathological analyses indicative of environmental contamination in Mullet, Mugil liza, from Southeastern Brazil

Mullet (Mugil liza) were sampled in five different areas along the Guanabara Bay, southeastern Brazil, classified as non-contaminated, moderately contaminated and contaminated. Morphometric (Fulton condition factor, relative condition factor and weight to length scaling coefficient) and organosomatic (hepatosomatic index) indices of environmental stress were analysed. Fish from the differentially contaminated areas show statistically different Fulton and relative condition factors and hepatosomatic indices, but not the weight to length scaling coefficient. The Kn and the FCF followed the same trend, with fish from São Gonçalo (1.07 ± 0.04 and 0.89 ± 0.03), Itaipu (0.84 ± 0.01 and 0.86 ± 0.01) and the Rodrigo de Freitas Lagoon (1.03 ± 0.01 and 0.87 ± 0.20) showing higher FCFs than fish from Magé (0.96 ± 0.01 and 0.81 ± 0.01). Fish from Itaipu showed significantly higher HSI values than the other sampling sites (1.68 ± 0.07), with fish from Olaria and Ipiranga showing the lowest (1.56 ± 0.12 and 1.60 ± 0.07, respectively).

Inefficacy of piracetam in the prevention of painful crises in children and adolescents with sickle cell disease

Analgesia and hydration remain the only safe treatment for painful crises of sickle cell disease; hydroxyurea is effective, but the toxicity is still a problem. Piracetam is a nootropic drug that has reportedly been effective and non-toxic in sickle cell patients, but most studies were not placebo-controlled and included a small number of patients. The present study evaluated the drug in a double-blind crossed placebo-controlled clinical trial in 73 children and adolescents suffering from moderate to severe painful crises for 13 months. Information regarding frequency and severity of pain was acquired through monthly clinical evaluation, visits and house calls, and 4,300 weekly questionnaires filled out by the patients in their domiciles. A monthly pain score was calculated for each patient. Pain was the most frequent adverse manifestation of the disease stressing its significant bio-psycho-social impact. Although nearly all patients and relatives reported a better clinical course throughout the whole study, the drug was ineffective in the prevention of painful crises. This placebo effect may be ascribed to an unplanned and unsystematic 'cognitive-behavioural' management of the children. The pain score in the second semester of the study - both in the experimental and in the control groups - was significantly smaller than that in the first semester. In conclusion, piracetam was found to be ineffective in the prevention of painful crises; a powerful placebo effect due to adequate patient care was demonstrated.